UV absorbance(A) of self-assembled films of poly(dimethyldiallyl ammonium chloride)(PDDA) and poly(styrene sulfonate)(PSS) with various concentrations of polyelectrolyte(c__P) at different concentrations of sodium chloride was investigated. It was found that the A～c__P curves display a discontinuous phenomenon. And the turning point concentration, at which the A～c__P curve starts to display a discontinuous phenomenon, is in good agreement with the critical concentration c* of PSS or PDDA polyelectrolyte solutions. The results above attribute to the change of chain shape of polyelectrolytes in solutions caused by c__P and c(NaCl). Thus, it is inferred that chain shape of polyelectrolyte in solutions affects the thickness of PSS/PDDA multilayer films.
Polyacrylonitrile-block-poly（methyl acrylate）（P（AN-b-MA）） was synthesized by reversible addition-fragmentation chain transfer （RAFT） polymerization employing macro-RAFT agent （PAN-RAFT） as the chain transfer agent and azobis（isobutyronitrile） （AIBN） as the initiator. A linear relationship between ln（[M]0/[M]1） and reaction time was observed. The molecular structure of P（AN-b-MA） was characterized by ^1H-NMR, element analysis, FTIR and SEC. The molecular weight distribution （MWD） was less than 1.40, the Mn could be controled from 0.733 to 4.834×10^4, and the molar content of MA in P（AN-b-MA） were from 15.6 to 75.0 percentage, respectively.
